3x 4k Monitors with more then 120Hz each... possible?

[DeParty93]

Hey,

 

I have 3 Samsung Odyssey Neo 4k 240Hz monitors and run all of them in 4k 120Hz mode powerd by my MSI RTX 4090 Suprim X. No problems here. Prior to me getting a 3rd monitor I had 2 of them running at 4k 240Hz. also no problem here. 

 

My Question now is: Theoretical there should be a 4k 120Hz headroom still there to run a 4th 4k 120Hz Monitor right? So would it be possible to give the 3 monitors each an extra 40Hz adding up to 160Hz per monitor or maybe 144Hz per monitor or something like this? or would it be possible to run one of the monitors at 240Hz and the other ones at 120Hz? 

If possible How would I set this up? would I have to do it in Windows? or do I use Gforce Experiance?

 

Or am I completely wrong here? Thanks in advance!

[Shimejii]

As long as you have 3 DP 1.4a connectors it should run each one at its rated speed of 240hz. Although Nvidia cards have had some issues with 4k 240hz displays so if you have funky behavior its not the displays its probably the GPU since these should have been DP 2.0 but they choice against it.

[DeParty93]

No, i dont have a Problem with 3x 4K 120Hz or 2x 4k 240Hz. 
DP1.4a should be able to do 8k 120Hz Right?
 

so, 1x 8k@120Hz = 2x 4k@240Hz = 4x 4k@120Hz and also = 3x 4k@160Hz. 

 

But im running 3x 4K@120Hz so i sould habe one extra 4K@120Hz extra to give to the other Monitors right?

 

[Brooksie359]

26 minutes ago, DeParty93 said:

No, i dont have a Problem with 3x 4K 120Hz or 2x 4k 240Hz. 
DP1.4a should be able to do 8k 120Hz Right?
 

so, 1x 8k@120Hz = 2x 4k@240Hz = 4x 4k@120Hz and also = 3x 4k@160Hz. 

 

But im running 3x 4K@120Hz so i sould habe one extra 4K@120Hz extra to give to the other Monitors right?

 

I am super confused. You are not running these from the same displayport connections so why are you treating it like they share bandwidth? 

[DeParty93]

11 minutes ago, Brooksie359 said:

I am super confused. You are not running these from the same displayport connections so why are you treating it like they share bandwidth? 

I have no plan. i am asking if it is possible to run the 3 displays each in 4k@160 or each in 4k@144 or been two in 4k@120 and one of them in 4k@240 and if yes how I set it up. the rest around is just my math logic why I think it should. but I honestly don't know.

 

and I am running them off of the same 4090. so I guess that's why.

[Kilrah]

Each port is independent, the GPU as a whole doesn't care about how many are used at what res/speed.

[DeParty93]

11 minutes ago, Kilrah said:

Each port is independent, the GPU as a whole doesn't care about how many are used at what res/speed.

so, what would the math be? does anyone know the truly correct math and can find out if it would be possible? Because doubble 4k@240Hz was possible. so it wouldn't be a issue of the singular ports. Its more the limitations of what the 4090 can put out. so my question still stands: can I run 3x 4k@144Hz or 3x 4k@160Hz or 2x 4k@120 + 1x 4k@240Hz?

[Brooksie359]

1 hour ago, DeParty93 said:

I have no plan. i am asking if it is possible to run the 3 displays each in 4k@160 or each in 4k@144 or been two in 4k@120 and one of them in 4k@240 and if yes how I set it up. the rest around is just my math logic why I think it should. but I honestly don't know.

 

and I am running them off of the same 4090. so I guess that's why.

I think the point I am trying to make is that if displayport can support 4k 240hz then that means if you have 3 displayport connections on your card then they should be able to all run at 4k 240hz. You are dividing the amount of information one displayport can transfer by 3 or 4 for no reason. Sure if it was all running from one displayport connection then you would divide but 3 separate displayports mean you have 3 separate connections that support 4k 240hz. 

[DeParty93]

8 minutes ago, Brooksie359 said:

I think the point I am trying to make is that if displayport can support 4k 240hz then that means if you have 3 displayport connections on your card then they should be able to all run at 4k 240hz. You are dividing the amount of information one displayport can transfer by 3 or 4 for no reason. Sure if it was all running from one displayport connection then you would divide but 3 separate displayports mean you have 3 separate connections that support 4k 240hz. 

that was my first thought to but turns out the 4090 has a hard limit how much data it can process. turns out it is something in the neighbourhood of 2x 4k@240Hz or 4x 4k@120Hz. I have tried to run 3 Screens at 4k@240Hz but it didn't work at all and I found on forums that I have to set my screens to 120 Hz. my question is why 120Hz? why not 160Hz or 144Hz? 

 

 

[Brooksie359]

1 hour ago, DeParty93 said:

that was my first thought to but turns out the 4090 has a hard limit how much data it can process. turns out it is something in the neighbourhood of 2x 4k@240Hz or 4x 4k@120Hz. I have tried to run 3 Screens at 4k@240Hz but it didn't work at all and I found on forums that I have to set my screens to 120 Hz. my question is why 120Hz? why not 160Hz or 144Hz? 

 

 

Oh diplayport 1.4 normally supports 4k 120hz without any workarounds. I think the workaround that the gpu needs to do so it can make 4k 240hz must have some limitations how many monitors it can do at once. Granted I am not sure why you would need multiple monitors to go at 4k 240hz since most people only use one monitor for gaming. Also I would have thought that if the max it could do was 2 monitors at 4k 240hz that if you have 3 monitors you would be able to do 2 at 240hz and the last one at 120hz just fine but I guess I am not sure how the limitation works so maybe that isn't possible. 

[DeParty93]

17 hours ago, Brooksie359 said:

Oh diplayport 1.4 normally supports 4k 120hz without any workarounds. I think the workaround that the gpu needs to do so it can make 4k 240hz must have some limitations how many monitors it can do at once. Granted I am not sure why you would need multiple monitors to go at 4k 240hz since most people only use one monitor for gaming. Also I would have thought that if the max it could do was 2 monitors at 4k 240hz that if you have 3 monitors you would be able to do 2 at 240hz and the last one at 120hz just fine but I guess I am not sure how the limitation works so maybe that isn't possible. 

its DP1.4a as far as I know. and for the reason why because I like high refreshrates and smooth motion on all my screens. and if its possible I would like to get it. so the other thing is also what you said I have tried and with a few restarts, windows now Identifys the main Screen as a 4k@239.57Hz Monitor and I works I think. lets see how stable it will run in the future. i will update as soon as I encounter issues. also does anyone know why it identyfys as a 4k@239.57Hz Monitor and not a 4k@240Hz Monitor the nubre seems odd to me somehow.

[Glenwing]

NVIDIA has a limit of 4 displays per card. If the resolution/refresh rate is high enough to require DSC, then it counts as 2 displays. 4K 240 Hz requires DSC, so you will be limited to 2 displays (each counts as 2, so you will reach the max limit of 4).

 

4K 120 Hz is the max limit of DP 1.4 without DSC being required, so that is the most you can do if you want 3 or 4 of these displays.

 

https://nvidia.custhelp.com/app/answers/detail/a_id/5338/~/using-high-resolution%2Frefresh-rate-displays-with-vesa-display-stream

Quote

When a display is connected to the GPU and is set to DSC mode, the GPU may use two internal heads to drive the display when the pixel rate needed to drive the display mode exceeds the GPU’s single head limit. This may affect your display topology when using multiple monitors.  For example if two displays with support for DSC are connected to a single GeForce GPU, all 4 internal heads will be utilized and you will not be able to use a third monitor with the GPU at the same time.

 

[DeParty93]

1 hour ago, Glenwing said:

NVIDIA has a limit of 4 displays per card. If the resolution/refresh rate is high enough to require DSC, then it counts as 2 displays. 4K 240 Hz requires DSC, so you will be limited to 2 displays (each counts as 2, so you will reach the max limit of 4).

 

4K 120 Hz is the max limit of DP 1.4 without DSC being required, so that is the most you can do if you want 3 or 4 of these displays.

 

https://nvidia.custhelp.com/app/answers/detail/a_id/5338/~/using-high-resolution%2Frefresh-rate-displays-with-vesa-display-stream

 

but i got it to run at 2x 4k@120Hz and 1x 4k@239.57Hz but the 3rd monitor seems a bit dimm...

 

[DeParty93]

Oh I just wanted to add, I set the Monitors to : 2x 4k@119,88Hz and 1x 4k@239,57Hz and it runs perfectly including HDR and all Monitors are Perfectly bright. Even the Third Monitor wich was dimm before is normal again.

 

Would that be a topic for a Tech Quicky Episode? Why is that what's with that random nombres? 119,88Hz and 239,57Hz how do they come to be why not 120Hz and 240Hz and so on...

[Glenwing]

On 2/1/2024 at 12:23 PM, DeParty93 said:

but i got it to run at 2x 4k@120Hz and 1x 4k@239.57Hz but the 3rd monitor seems a bit dimm...

 

Right, so each of the 4K 120 Hz is 1 display, because it doesn't need DSC, and the 4K 240 Hz counts as 2, so 1+1+2 = 4, which doesn't exceed the max limit, so it's allowed.

 

On 2/1/2024 at 12:40 PM, DeParty93 said:

Oh I just wanted to add, I set the Monitors to : 2x 4k@119,88Hz and 1x 4k@239,57Hz and it runs perfectly including HDR and all Monitors are Perfectly bright. Even the Third Monitor wich was dimm before is normal again.

 

Would that be a topic for a Tech Quicky Episode? Why is that what's with that random nombres? 119,88Hz and 239,57Hz how do they come to be why not 120Hz and 240Hz and so on...

It's 120 and 240 times 1000/1001 which is a standard value for historical reasons related to the transition from monochrome to color television in the US.